x86, cacheinfo: Fixup L3 cache information for AMD multi-node processors

L3 cache size, associativity and shared_cpu information need to be
adapted to show information for an internal node instead of the
entire physical package.

Signed-off-by: Andreas Herrmann <andreas.herrmann3@amd.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>